Dispelling nutrition myths, ranting, and occasionally, raving


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Cruciferous crusaders or (not so) superfoods? The truth about veggies & cancer

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Did you hear the news? Last week it was announced that there’s no evidence of a link between vegetable and fruit consumption and risk of developing cancer. This proclamation was based on the results of a large-scale analysis of data from cohort studies in Japan.

Before everyone rejoices and throws the contents of their crispers in the compost, opting instead to have ice cream for supper maybe we should take a closer look at the original research.

The first caution I’d make is that this is based on a study of people in Japan. Because the average Japanese diet and lifestyle differs significantly from our North American diet and lifestyle we can’t conclude that results seen in people in Japan will apply to people in Canada or the US, or pretty much any other country.

The second caution, and this is the big one, is that the frequency of consumption of vegetables and fruit used in the study was very different from what’s recommended here. The greatest consumption of veg and fruit recorded in the study was “almost daily”. Compare that to the recommended 8-10 servings per day in Canada’s Food Guide. Stating daily consumption of veg and fruit tells us very little about the true picture of veg and fruit consumption. This categorization allows a person who eats one apple a day (and no other veg or fruit) to be viewed as the same as a person who eats veg and/or fruit at every meal and snack and consumes a wide variety of produce. The method of categorization in this study really only allows us to conclude that at minimal consumption levels, eating vegetables and fruit doesn’t appear to provide protection against cancer when compared to eating vegetables and fruit infrequently (or almost never??). The fact that almost never is even an option makes me wonder about the accuracy of self-reporting and the possibility that people in that group could be more likely to succumb to ailments such as scurvy before cancer would have a chance to get to them.

The third point to mention (although hopefully I don’t need to) is that absence of evidence is not evidence of absence. Just because this study didn’t find a relationship between the consumption of vegetables and fruit and the development (or prevention) of cancer doesn’t mean that there isn’t a connection between the two. It’s possible that using different parameters might show that a greater consumption of vegetables is linked to a decreased risk of certain types of cancer.

The final point that I think is important to make is that we don’t eat food in order to prevent cancer. Even if this study is showing us that eating vegetables and fruit doesn’t confer protection against cancer upon us (and I’m not even remotely convinced that it does) there are plenty of other good reasons to eat vegetables and fruit. Vegetables and fruit provide us with many vitamins and minerals that are vital to the function of our bodies. They provide us with fibre which is essential for gut health. They provide us with water and energy, which are both necessary for our survival. They also add flavour, colour, and variety to our diets making meals and snacks enjoyable. All this to say that while cookies are delicious they still aren’t a balanced nutritious meal. Vegetables and fruit still have important roles to play in keeping us healthy.


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Is store bought baby food better than home cooked?

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When I saw this article in the Daily Mail (yeah, I know) last week I knew that I had to read the original research to see what it said. As a dietitian I’m always trying to encourage people to cook their own meals. When I talk to mums about introducing their babies to solid foods I suggest that they see it as an opportunity to enjoy balanced meals as a family. Just what I need is headlines and articles proclaiming that pre-made store bought baby food is healthier than what ever they might be preparing at home.

I was frustrated to be unable to see the list of cookbooks the authors used in this study. The link just takes me to Amazon, and the list of the most popular baby food cookbooks they used was complied in 2013 so any results I might find could be considerably different today. Naturally, I worry about the use of baby food cookbooks as a comparison to ready-meals as they tend to be written by people with limited (or no) nutrition credentials (*cough* Pete Evans *cough*. Cookbooks are also quite unlikely to provide a true picture of what parents are feeding their children.

The obvious conclusion to draw from the study is that home cooked meals are superior (from both a cost and nutritional standpoint) to ready meals (at all ages) provided parents are preparing foods without added salt and sauces. The authors didn’t seem to reach this conclusion though. Perhaps the disingenuous comparison between cookbook recipes and ready meals, and the conclusion that ready meals may be better for babies, had something to do with the funding they received from Interface Food and Drink, an organization aimed at connecting the food and drink industry with researchers.

So, we know that home cooked meals can be healthy if parents don’t waste their money on special baby cookbooks. I think that it’s also important to note that the researchers were comparing quantities based on recipe yields and packages, not what babies are actually eating. Even if babies were eating recipes prepared from these cookbooks, they may not be eating every bite. Babies are much better than us adults at knowing when they’re full. If parents are respecting their babies cues and only feeding them as much as they show a desire to eat then it shouldn’t matter how much a recipe makes, or how much is in a package.

The true message from this study should be that you don’t need to waste your money on baby food cookbooks. Nor do you need to waste your money on packaged baby foods. Most babies will thrive on, and enjoy, a variety of simply prepared “normal” foods.

If you’re looking for more information on starting your baby on solids, I recommend visiting Best Start as well as watching this video from Toronto Public Health. If possible, sign-up for an infant feeding class through your local public health office.

 


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Aloe vera: healing or harmful?

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Image by Andreas Issleib on flickr. Used under a Creative Commons Licence.

A little while ago when I was looking for blogspiration a friend told me to take a look at a certain “nutritionist” on twitter. Since then, I’ve had her on my back burner because she certainly looked like she would have some good blog fodder (cured her incurable illness through diet) but I couldn’t be bothered to look through all her posts. Well, today’s the day I move her to the front burner.

I was reading her post on the healing properties of aloe. I found myself hoping that she would provide a balanced picture because I didn’t really want to write about aloe. Sadly, she did not, so here we are. As I feel that simply extolling the virtues of a food, without providing cautions is irresponsible, even if you don’t have a regulatory body protecting the public from you. Sorry, sorry, I digress.

In her post she writes about the magical properties of aloe: anti-viral, anti-bacterial, anti-inflammatory. Unfortunately, there she didn’t link to any research so I can’t comment on the quality of the studies used to make these claims. As far as I can tell, to date there’s been very little (if any) research on human subjects. However, some in vitro studies and animal have shown some promise when it comes to the anti-viral (1, 2) and anti-microbial (3, 4) properties of aloe vera. Of course, based on the current research, there’s no way to know what dose or form of aloe would (if at all) be effective in humans. It’s entirely possible that oral ingestion of aloe would not have any positive benefits in relation to viruses and bacteria.

Some mouse studies and in vitro have shown promising wound healing and anti-inflammatory effects of aloe vera (when administered both topically and orally) (5, 6). Again, there has yet to be any conclusive research done in humans.

Okay, it sounds a bit promising but… Then come the concerns. Before you start adding a handful of aloe vera plant to your smoothie you should be aware that the exterior portion of the leaf has a laxative effect. There are other longer lasting concerns about aloe vera consumption than diarrhea. My friend Helen has written about many of them on her blog Food and Nonsense. These include a risk of cancer and impaired liver function. Over at Examine, the only conclusive research they’ve found so far for aloe supplementation is for increased intestinal motility (i.e. to combat constipation). The Mayo Clinic provides a long list of cautions against the ingestion of aloe vera products, including the risk of inducing uterine contractions in pregnant women. I’ve also blogged about the consumption of aloe vera juice in the past.

I believe that my final statement in that post stands the test of time: Just because it’s “natural” doesn’t mean it’s good for you.

 


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Can eating chocolate reduce your risk of developing type 2 diabetes?

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A recent study in the British Journal of Nutrition reportedly showed that regular consumption of chocolate could reduce the risk of developing type 2 diabetes. Naturally, I wondered if that was really what the study showed.

Looking at the study, there were a few things that stood out to me. The research was done using a food frequency questionnaire, a notoriously inaccurate measure of diet. Besides the fact that this measure is often inaccurate, is the fact that we couldn’t tell if it distinguished between types of chocolate consumed. While the authors made much of the potential link between polyphenols in chocolate and reduced risk of T2 diabetes, we don’t know if the study actually looked at types of chocolate that were rich in polyphenols. By the article, we can’t tell if they made any distinction between dark chocolate, milk chocolate, white chocolate, chocolate bars, chocolate cake, chocolate ice cream, and so on. Without accounting for different types of chocolate (many of which contain negligible quantities of polyphenols) there’s no way to attribute the reduced risk of T2 diabetes to the consumption of polyphenol-rich chocolate.

Perhaps more importantly though, there’s no way we can draw any conclusions regarding causation. This wasn’t a longitudinal study so we don’t know if people who have T2 diabetes are avoiding eating chocolate (quite plausible) or if there’s some other reason why people who eat chocolate are less likely to have T2 diabetes than people who don’t.

I also wondered about the true significance of the results. For that I consulted with my math expert, Scott. His take was that the sample size wasn’t very large and that it was limited to Luxembourg. This makes it difficult to generalize the results to populations outside of Luxembourg, for example, North America, as there could be other differences between Canadians and Americans and Luxembourgians (is that the right term?) that would make it impossible to apply the findings to our population.

He also said:

Although they followed proper testing and analysis, I’d be concerned about variables that they did not include in this study, such as location and what might be in their environment or particular diet (food items not mentioned) that may distinguish this sample from say a sample in North America. I am also wary anytime the analysis includes a questionnaire or feedback rather than pure conclusions based on observed tests and results. As you well know from interviewing people at stats can, there are more than admitted “fake” stats and responses… Yes, I do see a correlation between the two, I would require further testing to be conclusive on the hypothesis.

I followed up this analysis by asking him if he thought the standard deviations were of concern. To my untrained eye, I thought that it was possible that the range for each result was large enough that there might, in actuality, be no real difference between each group. Scott said:

I would support that claim, you would want the SD to be much closer to the mean than those results. I suspect the SD would fluctuate with any other sample size tested under those conditions.

And there you have it. While it’s possible that there’s a reduced risk of having diabetes to chocolate consuming Luxembourgians, there’s more research to be done before anything definitive, especially for other populations, can be concluded.


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Follow Friday @nutritionwonk

If you enjoy reading topical nutrition blogs (and if you don’t, um… you may be in the wrong place) I recommend you check out one of the newer kids on the block Nutrition Wonk (aka Katherine aka @smarfdoc on twitter).

As a grad student studying nutrition biochemistry and epidemiology, Katherine takes a science-focused approach to writing about popular nutrition news. She does an excellent job of writing in a way that’s both accessible to the layperson and informative to those in the field.

Looking for an unbiased assessment of the latest article on the war on sugar? A thorough take-down of Laura Prepon’s diet book? How about an interview with Dr Yoni Freedhoff? She’s got it all, and more.

I’m looking forward to reading her future posts and I hope you will as well!